DUPLEX GAS PIPELINE THICKNESS CALCULATION
DUPLEX GAS PIPELINE THICKNESS CALCULATION
(OP)
I have to calculate the thickness for a gas pipeline made in UNS S31803 (duplex). Design code shall be B31.8. Where I can take derating data for this material. Is it possible to consider data from ASME II sect.D? Or I can consider the derating pitcure on the DNV OS F101? Which is the preferrable approach?
Thanks for your help
Thanks for your help





RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
This is from the Introduction Section of B31.8:
Materials are listed in the Stress Tables only when
sufficient usage in piping within the scope of the Code
has been shown. Materials may be covered by a Case.
Requests for listing shall include evidence of satisfactory
usage and specific data to permit establishment of allowable
stresses or pressure rating, maximum and minimum
temperature limits, and other restrictions. Additional
criteria can be found in the guidelines for addition of
new materials in the ASME Boiler and Pressure Vessel
Code, Section II and Section VIII, Division 1,
Appendix B. [To develop usage and gain experience,
unlisted materials may be used in accordance with para.
811.2(b).]
So, IMO, IF you are designing to B31.8 AND you want to use the [presumably] unlisted S31803 duplex material THEN you follow B31.8 paragraph 811 (I hesitate to just say 811.2(b) as there is pertinent information in the rest of para 811.)
Patricia Lougheed
******
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RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
I can quote these,
With the difficulties I see indicated in bold text, and not being totally sure if the last (b) clause is intended to include pipe.
I know of no operators that are so adventureous to push these clauses for one reason or another, so I wouldn't recommend that you do it either. I can only see increased potential delays for your project, if not things that may be worse. Can't you find anything to use that is already in the list?
We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
Of course, there also exists the possibility of designing to some other standard, if the client agrees.
Patricia Lougheed
******
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RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
Everybody knows that S31803 is very common nowdays and it's very strange that ASME B31.8 consider that material non-standard in the 2010 version!!!
I don't think I am working on the first gas pipeline in the world made of duplex. So I think that somebody have already made calculatioin and design consideration without any additional wasting time tests.
It is also obvious that when you have to develop a project you can't lost months to permorm tests on materials like S31803 that everibody knows and thousand and thousans articles was written and tests were performed.
So I need a common pratical calculation solution with no tests and no abstract discussion on the absurd theoretical paragraph of ASME B31.8.
Sorry if I was rude, and my best apologies for this, but I think that some very glorious standards like B31.8 should be updated every now and then and not only minor corrections in 10 years!! Thanks for your support anyway
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
So, if you're going to do gas pipelines, the sooner you get used to it, the better. My best advice is to follow the code, if you like collecting regular paycheques.
We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
If your line is a used for gas gathering and is not subject to 49CFR 192, B31.3 may be used. Dupelex stainless steel was used in North Slope gathering systems designed per B31.3 years ago.
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
You're the person trying to do the design. Railing against the ASME standard gets you nowhere. Both BigInch and I have outlined the process in B31.8 for you to use the material you want. That's the only way you can use your beloved duplex and still meet the standard. We're not going to tell you that either of your approaches are acceptable, because they aren't.
As I see it, your options are
1) Follow B31.8 and use a material permitted by the standard.
2) Follow B31.8 and the provisions in Section 811 for unapproved materials to show that your choice of material is acceptable.
3) Convince your client that a different specification is more appropriate. For example, if you are in Europe, there might be an EN standard that applies. Here's a Wikipedia article that purportedly gives a list of EN standards: http://en.wikipedia.org/wiki/List_of_EN_standards
4) Go rogue, use the material you want, and ignore the B31.8 standard. If you do this, be prepared to accept the consequences. Just to be perfectly clear, I DO NOT ADVOCATE THIS OPTION.
Patricia Lougheed
******
Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
Best regards
Morten
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
Its Gabriel trying to use B31.8 in Norway that's creating the problem.
We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer
RE: DUPLEX GAS PIPELINE THICKNESS CALCULATION
I do not believe that was the leaker. The 2205 gathering line was installed around 1990 for the Kuparak [unsure of spelling] field. I was involved in the original Engineering and mandating that automatic orbital welding be performed in the field.